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When does determinacy imply expectational stability?


  • James B. Bullard
  • Stefano Eusepi


In the recent literature on monetary and fiscal policy design, adoption of policies that induce both determinacy and learnability of equilibrium has been considered fundamental to economic stabilization. We study the connections between determinacy of rational expectations equilibrium, and expectational stability or learnability of that equilibrium, in a general class of purely forward-looking models. We ask what types of economic assumptions drive differences in the necessary and sufficient conditions for the two criteria. We apply our result to a relatively general New Keynesian model. Our framework is sufficiently flexible to encompass lags in information, a cost channel for monetary policy, and either Euler equation or infinite horizon approaches to learning. We are able to isolate conditions under which determinacy does and does not imply learnability, and also conditions under which long horizon forecasts make a clear difference to conclusions about expectational stability. The sharpest result is that informational delays break equivalence connections between determinacy and learnability.

Suggested Citation

  • James B. Bullard & Stefano Eusepi, 2009. "When does determinacy imply expectational stability?," Working Papers 2008-007, Federal Reserve Bank of St. Louis.
  • Handle: RePEc:fip:fedlwp:2008-007

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    References listed on IDEAS

    1. McCallum, Bennett T., 2007. "E-stability vis-a-vis determinacy results for a broad class of linear rational expectations models," Journal of Economic Dynamics and Control, Elsevier, vol. 31(4), pages 1376-1391, April.
    2. Schmitt-Grohe, Stephanie & Uribe, Martin, 2007. "Optimal simple and implementable monetary and fiscal rules," Journal of Monetary Economics, Elsevier, vol. 54(6), pages 1702-1725, September.
    3. Bruce Preston, 2005. "Learning about Monetary Policy Rules when Long-Horizon Expectations Matter," International Journal of Central Banking, International Journal of Central Banking, vol. 1(2), September.
    4. George W. Evans & Seppo Honkapohja, 2003. "Expectations and the Stability Problem for Optimal Monetary Policies," Review of Economic Studies, Oxford University Press, vol. 70(4), pages 807-824.
    5. Marcet, Albert & Sargent, Thomas J., 1989. "Convergence of least squares learning mechanisms in self-referential linear stochastic models," Journal of Economic Theory, Elsevier, vol. 48(2), pages 337-368, August.
    6. Bullard, James & Mitra, Kaushik, 2002. "Learning about monetary policy rules," Journal of Monetary Economics, Elsevier, vol. 49(6), pages 1105-1129, September.
    7. Stephanie Schmitt-Grohé & Martín Uribe, 2006. "Optimal Simple and Implementable Monetary and Fiscal Rules: Expanded Version," NBER Working Papers 12402, National Bureau of Economic Research, Inc.
    8. Preston, Bruce, 2008. "Adaptive learning and the use of forecasts in monetary policy," Journal of Economic Dynamics and Control, Elsevier, vol. 32(11), pages 3661-3681, November.
    9. John B. Taylor, 1999. "Monetary Policy Rules," NBER Books, National Bureau of Economic Research, Inc, number tayl99-1, January.
    10. Preston, Bruce, 2006. "Adaptive learning, forecast-based instrument rules and monetary policy," Journal of Monetary Economics, Elsevier, vol. 53(3), pages 507-535, April.
    11. Stefano Eusepi & Bruce Preston, 2010. "Central Bank Communication and Expectations Stabilization," American Economic Journal: Macroeconomics, American Economic Association, vol. 2(3), pages 235-271, July.
    12. McCallum, Bennett T., 1999. "Issues in the design of monetary policy rules," Handbook of Macroeconomics,in: J. B. Taylor & M. Woodford (ed.), Handbook of Macroeconomics, edition 1, volume 1, chapter 23, pages 1483-1530 Elsevier.
    13. Blanchard, Olivier Jean & Kahn, Charles M, 1980. "The Solution of Linear Difference Models under Rational Expectations," Econometrica, Econometric Society, vol. 48(5), pages 1305-1311, July.
    14. Woodford, Michael, 2003. "Comment on: Multiple-solution indeterminacies in monetary policy analysis," Journal of Monetary Economics, Elsevier, vol. 50(5), pages 1177-1188, July.
    15. Ravenna, Federico & Walsh, Carl E., 2006. "Optimal monetary policy with the cost channel," Journal of Monetary Economics, Elsevier, vol. 53(2), pages 199-216, March.
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    Cited by:

    1. Cho, Seonghoon, 2015. "Determinacy and e-stability under reduced-form learning," Economics Letters, Elsevier, vol. 128(C), pages 69-71.
    2. Ascari, Guido & Florio, Anna & Gobbi, Alessandro, 2017. "Transparency, expectations anchoring and inflation target," European Economic Review, Elsevier, vol. 91(C), pages 261-273.
    3. Nakagawa, Ryuichi, 2015. "Learnability of an equilibrium with private information," Journal of Economic Dynamics and Control, Elsevier, vol. 59(C), pages 58-74.
    4. Ellison, Martin & Pearlman, Joseph, 2011. "Saddlepath learning," Journal of Economic Theory, Elsevier, vol. 146(4), pages 1500-1519, July.

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    Rational expectations (Economic theory);

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